Patterson Viaduct

The Patterson Viaduct is a railroad bridge spanning the Patapsco River in Howard and Baltimore County, composed of four stone arches approximately 110 meters long. The structure displays the classical arch bridge design of the 1800s, with thick stone piers supporting a curved roadway.

The viaduct was constructed between May and December 1829 as part of the Baltimore and Ohio Railroad's Old Main Line, marking early American railroad development. Following the 1868 flood that damaged the original structure, portions of the arch were incorporated into a new bridge design.

The structure is named after William Patterson, a B&O Railroad director, and demonstrates the construction techniques and stone materials typical of early American railroad infrastructure.

The site is accessible from the Grist Mill Trail, where visitors can cross the Patapsco River on a modern pedestrian pathway. The location requires care with uneven terrain and changing weather conditions, particularly during or after rain.

One of the original stone arches survived the 1868 flood and was later reused by engineer Wendel Bollman in an entirely new steel truss design. This unexpected transition from classical arch architecture to modern truss engineering is still visible at the site today.

Location: Howard County

Location: Baltimore County

Official opening: December 1829

Made from material: stone

GPS coordinates: 39.24890,-76.76470

Latest update: December 12, 2025 07:59